Missense variants in the SAND domain of DEAF1 have been previously reported in association with dominant intellectual disability phenotypes, and a severe recessive epilepsy phenotype.31,32 The same allele identified in subject #9 (p.G212S) was recently reported in a 15-year-old male with developmental regression and seizures.33 Functional studies suggest that this allele eliminates both DEAF1 transcriptional repression activity and DEAF1–DNA interactions. This evidence concerns the gene DEAF1 and Intellectual disability.